Using early antipsychotic response to predict treatment outcome in patients with first-episode psychosis

Abstract

Antipsychotic medications are highly effective in the treatment of patients experiencing first-episode psychosis. However, some patients do not respond to the first antipsychotic medication they are given, and may require trials of several drugs before an effective treatment is found. While antipsychotics may take months to achieve their full effect, recent evidence suggests that it is possible to predict whether a patient will respond to a particular drug by assessing early response after as little as 2 weeks of treatment. Assessing early antipsychotic response has the potential to improve treatment strategies for psychotic patients, but there is still a great deal of uncertainty about what early response can and cannot predict, and how the predictive value of early response differs among drugs and patient populations. The work presented in this thesis addresses some of the most pressing questions about early antipsychotic response in several samples of antipsychotic-naive patients with first-episode psychosis. This work demonstrates that: (1) the appropriate time point at which to assess early response differs between antipsychotic drugs; (2) early improvement in depressive and manic symptoms predicts treatment outcome, while early improvement in anxiety symptoms may not; (3) strong early response is associated with decreased rates of extrapyramidal side-effects; (4) early antipsychotic response can predict long-term treatment outcome at least 2 years after treatment initiation; (5) the appropriate time point at which to assess early response differs in patients who receive antidepressant treatment in addition to antipsychotic treatment; (6) patients with a poor early response may benefit from being switched to another antipsychotic, particularly one with a distinct receptor binding profile. These results highlight several weaknesses of the current literature, suggesting that early antipsychotic response should be assessed differently depending on the psychiatric symptom profile of each patient and the specific medications that are being used. However, the data presented here also emphasize the potential therapeutic value of assessing early response. The ability of early response to predict treatment outcome appears to be even greater than previously thought, and understanding how to appropriately use this important assessment to guide treatment strategies may improve the efficiency and efficacy of treatment for psychotic patients.